1. Field of the Invention
The present invention relates to a one-way clutch used in an automatic transmission and a method for manufacturing such a one-way clutch.
2. Related Background Art
FIG. 7 shows an example of a conventional one-way clutch assembly. In FIG. 7, in a one-way clutch assembly 520, an outer race 521 is defined by an inner peripheral portion of a cylindrical clutch hub 527, and a sprag 523 is disposed between the outer race 521 and an inner race 525 coaxial with the outer race. There are provided a ribbon spring 526 for biasing the sprag 523 in a radial direction, and an annular holder 528 for holding the sprag 523 and the ribbon spring 526.
At an axial side of the holder 528, an annular end bearing 529 having substantially U-shaped section is disposed between the outer race 521 and the inner race 525, thereby providing a proper clearance within which the sprag 523 can be rocked in a radial direction. Further, a pair of side plates 522 are mounted on axial outer ends of the end bearing 529, thereby regulating an axial movement of the holder 528. Incidentally, thrust washers 530 are disposed between the side plates 522 and opponent members, thereby providing axial positioning.
Further, the inner race 525 is provided with an oil path (shown by the arrow) which is a radial through-hole through which lubricating oil can be supplied in the one-way clutch.
In the one-way clutch of sprag type having the above-mentioned construction, when the inner race 525 is rotated in one direction, the inner race 525 is engaged by the outer race 521 via the sprag 523, thereby transmitting torque of the inner race 525 to the outer race 521. On the other hand, when the inner race 525 is rotated in an opposite direction, the sprag 523 is merely slid on an outer peripheral surface of the inner race 525, with the result that the torque is not transmitted.
In recent years, compactness, reduction of weight and reduction of cost of the automatic transmission have been requested. However, in the conventional construction, since the one-way clutch was merely combined with the automatic transmission, it was difficult to reduce the number of parts.
Therefore, an object of the present invention is to achieve compactness, reduction in weight, improvement in productivity and reduction in cost regarding an automatic transmission by matching a construction of a one-way clutch with a purpose of usage to meet such requirement.
To achieve the above object, in the present invention, an outer race of a one-way clutch of ratchet type using pawls as torque transmitting members is provided on a case of an automatic transmission. More specifically, the present invention is characterized by a one-way clutch for an automatic transmission, comprising an inner race, an outer race disposed in coaxial with the inner race and rotated relative to the inner race, recessed portions formed in an outer periphery of the inner race or an inner periphery of the outer race along a circumferential direction, pawls engaged by the recessed portions, and biasing members for biasing the pawls toward the recessed portions, and wherein the outer race is provided on a case of the automatic transmission.
Further, in the present invention, the outer race or bush of the one-way clutch may be integrally formed with the case of the automatic transmission.
More specifically, the present invention is characterized by a one-way clutch for an automatic transmission, comprising an inner race, an outer race disposed in coaxial with the inner race and rotated relative to the inner race, torque transmitting members disposed between the inner and outer races and adapted to transmit torque, and biasing members for promoting fitting of the torque transmitting members, and wherein the outer race is integrally formed with a case of the automatic transmission.
Further, the present invention is characterized by a one-way clutch for an automatic transmission, comprising an inner race, an outer race disposed in coaxial with the inner race and rotated relative to the inner race, torque transmitting members disposed between the inner and outer races and adapted to transmit torque, biasing members for promoting fitting of the torque transmitting members, a bush for supporting the torque transmitting members and the biasing members to provide a predetermined clearance between the inner and outer races, and wherein the bush is integrally formed with a case of the automatic transmission.
By the above-mentioned invention, it is not required that the outer race or the bush be provided separately, thereby achieving compactness, reduction in weight and reduction in cost regarding the one-way clutch.
Further, in the present invention, a one-way clutch of ratchet type may be used as the one-way clutch.
Further, the outer race or the bush provided on or formed integrally with the case may be made of aluminium. In this case, reduction in weight of the one-way clutch can be achieved, while maintaining strength.
In the present invention, the outer race or the bush provided on or formed integrally with the case may be obtained by die casting.
In this case, working steps can be simplified in comparison with a case where the outer race is formed separately.
In the present invention, a bearing portion may be provided on the outer race or the bush integrally formed with the case. In this case, not only it is not required that the bearing portion be provided separately to simplify assembling steps, but also reduction in weight and cost can be achieved.